Often sacrifices must be made to advance the cause of the Greater Good.
Or if you're less generous, "what does it matter what happens to a few of the peasants? We've got plenty of them as it is."
There's always moments in warfare when an army officer has to order one of his men to make an action that will in all likelihood result in his death, and this soldier will go forth and follow this command with the full knowledge that they'll not see the next day. Why does the officer give this command, why does the soldier follow it? Because their sacrifice will bring the war closer to its end and closer to victory.
In Western militaries the whole force consists of well-trained and elite volunteers, who follow their commanders because they want to. If they stop wanting to follow their leaders, the whole structure falls apart as a fighting force. Thus one cannot treat their soldiers like a Chinese warlord treated his peasant conscripts, or they will soon cease to be your soldiers.
That is the practicality of sacrificing for the greater good. There is an objective to work towards, and self-sacrifice is not enough - a leader must sacrifice others to advance to this goal, using all means possible to inspire their followers to achieve this good regardless of their own interests. It just so happens to be fortunate that was is pragmatic is also morally righteous, you're not going to want to follow a leader that is in plain terms a complete bellend.
Looking at the actions of Spanish or British leaders who sabotaged their own people's healthcares in order to advance their goals, it fails to be seen through this lens as advancing towards a greater good. These leaders are responsible for providing (in one of the most direct ways possible) for the welfare of their citizens, yet are actively willing to sabotage the welfare and destroy the lives of their own citizens just to discredit their political opponents' arguments. When the debates are over and they are reviewing their political careers, their citizens who had their lives ruined in such squabbling will have little consolation that any greater good was achieved in their sacrifice, all that was achieved was one bloke got to score more political points on the polling charts.
That is what separates those who are ruthless from those who are merely rotten. It is why I also believe the defeated leaders of last year, as distant as that year feels, failed so miserably - looking at how to destroy their opponents, not how to inspire their followers.